Thanks for this
Thanks for the years of knowledge everyone. Trying to get mine back on the road and here’s my Rock Auto parts order in case it helps anyone else. Subtotal before tax and shipping $157.02
Master Cylinder $37.79
CARDONE 131371
Wheel Cylinders $20.79 and $23.79 each
2- RAYBESTOS WC9344
2- RAYBESTOS WC9345
Front Hoses $10.90 each
2- DORMAN H36791
Rear Hose $8.27
ACDELCO 18J2119
Yes, great thread no matter how old it is. So I am also in the market for a new brake system on my modified truck. I found a 10-1331 is a remanufactured unit with a 1.125 bore. The 13-1331 is the same but new with a 1.125 bore. The 13-1371 has a 1 inch bore. I thought I would try the 1.125 bore given I am running 1 ton disc/drum axles under my truck. The 13-1331 new unit application at Rock Auto is a 1969 GMC K35/K3500 truck.
I am hoping the bigger bore is not a bad choice.
Mikeskates, I hope you post up how your brakes work later.
My 69 CJ has the original master cylinder powering big disc's and drums and works really well. No assist.
I have a couple Kaiser era wagoneer and J truck brake boosters new in the box. I will see if they mate up with the GMC 13-1331 master. I think I might prefer non power brakes though. I guess I will decide later. But I will get the master cylinder ordered. Thanks for all the postings with such great info.
So I am plumbing my brakes today. And I decided I was not sure which port went to what end of the truck. I am using the 69-70ish chevy master number 13-1331. Pushing fluid to a chevy disc dana 60 front and a dodge dana 70 rear with 13 inch drum brakes. So I check a couple dead FSJ's in the yard. Rear port to front brakes. My CJ rear port to rear brakes. The master cylinder has front cast into the front port. The brakes work flawlessly.
I search google... And I found this.
If the reservoirs are the same size, a good rule of thumb is that the front reservoir feeds the front brakes with GM master cylinders, while the rear reservoir feeds the front brakes on Ford and Mopar master cylinders.
So according to this statement (I read it on the internet!) The picture of Warthogs first post showing the brake lines from the master is wrong. He has the rear port to the front, front port to the back.
Does anyone know the accurate answer to this? Same size reservoirs front and back on the 13-1331. So far I am leaning towards front port to front brakes. This would be a good thing to clarify.
Anybody have a 68-70 chevy truck to check?
Found this...
Front to front, rear to rear on a GM master of that vintage. Please correct me if I am wrong.
http://67-72chevytrucks.com/vboard/s...d.php?t=756256
Last edited by Kaiserjeeps; March 19th, 2021 at 02:09 AM.
I'm using the 1331 with stock drum brakes, I used rear for front and front for rear, I found that information here on the brake conversion and my brakes are working fine.
That is what I have been reading. The bigger reservoir was for the excess displacement of brake fluid from pad wear and caliper travel. And that equal sized reservoirs were drum/drum master cylinders. So I looked up the master cylinder for the chevy K30 that my front disc brake front end came from and found that same chevy came with a 13x2.5 drum brake rear end like my Dodge dana 70. The master cylinder bore was 1 5/16!! So bigger bore means more pressure needed to push. Since the K30 used power brakes and I am not so far, I elected to stay with the GM 1331 I have in there at 1 1/8 dia. And it sounds like the 1331 may not care what end is what. My reading did show that the chevy or GMC truck that master came out of was indeed front to front and rear to rear.
So not really knowing for now, one thing that came to mind was paying attention while bench bleeding. When you just start pushing the piston, usually you get a noticeable squirt from one reservoir ahead of the other. That (if it happens) with this one model master should show that first pressure squirt to be the EDIT (rear) brakes. If it was equal pressure squirts than the master could be hooked up either or. Other than that I could not determine the answer just yet. I suppose I will find out and I will post my findings. It may be awhile yet. I am assembling the truck and then taking it apart for paint. Only later will I be filling the brake system. Unless I get a wild hair to find out for sure sooner than later. I appreciate you guys taking the time to respond.
Last edited by Kaiserjeeps; March 20th, 2021 at 11:39 PM.
The way I have always read and heard, the rear brakes get pressure first...once there is resistance at the rear...pressure starts to build up because the slack is taken out back there with the shoes or pads making contact with the drum or disc...then the front starts to get fluid. This way, since most of the braking is done up front anyway, at least the rears are in the system and active by the time the fronts kick in...
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